Confused about right app for Mac

I have PMS set up on a dedicated PC linked to a NAS in my study. However, I am confused about the best application to run on 2 Macbooks to access and sync the media (when away from the network)? I presume i don't download PMS again to each Macbook?

Or do I just use the web app in Safari? If I use the web app how do I access synced content when offline or away from my network?

Many thanks